Investigate accommodating ITK remote module dependencies

[tbirdso]

Investigate whether ITK remote module dependencies can be accommodated via input parameters.

Example 1: ITKBSplineGradient depends on ITKMeshToPolyData.

• For cxx builds, can we at minimum build against ITK's fixed MeshToPolyData version with CMake flags to enable the remote module?
• For Python builds, can we build ITKMeshToPolyData against ITK and point ITKBSplineGradient against the correct build tree?

Example 2: ITKUltrasound depends on MeshToPolyData, HigherOrderAccurateGradient, BSplineGradient, SplitComponents, and Strain.

• For cxx: Can we enable all remote modules for ITK to build in the correct order?
• For Python: Can we iteratively build each source in order (ordered list of Git repos, hashes/tags) before building ITKUltrasound?

[thewtex]

Another recommended test use / case is ITKTubeTK, which depends on ITKMinimalPathExtraction CC @aylward

[SimonRit]

Another one: RTK will depend on ITKCudaCommon (two remote modules) when RTKConsortium/RTK#492 is merged. cc @LucasGandel

[tbirdso]

@thewtex @SimonRit Thanks for the feedback. I am guessing that the remote module tags present in ITK (https://github.com/InsightSoftwareConsortium/ITK/tree/master/Modules/Remote) are not updated quickly enough to be useful here, i.e. it is a requirement that the external module under test can specify a commit hash for each of its ITK module dependencies.

For instance, rather than building ITK with -DModule_CudaCommon=ON such that CudaCommon is automatically fetched and built before building RTK, we would rather build ITK -> then fetch CudaCommon at a certain commit tag and build -> then RTK.

Do you agree that it is necessary to allow the user to specify the hash to use for each ITK module dependency?

[SimonRit]

If I understand your question correctly, you can specify the module tags manually at configuration with, e.g., Module_RTK_GIT_TAG, see here.

[dzenanz]

That is good enough for C++ building and testing. For Python package building it is not so simple.

[thewtex]

#tbirdso has implemented this in main, documented in the README.